Vacuum valves for substantially gas-tight closure of a flow path which leads through an opening in a valve housing are known in different embodiments from the prior art. Vacuum gate valves are used in particular in the area of IC and semiconductor manufacture, which must take place in a protected atmosphere as far as possible without the presence of contaminating particles. For example, in a manufacturing plant for semiconductor wafers or liquid crystal substrates, the highly sensitive semiconductor or liquid crystal elements pass sequentially through a plurality of process chambers in which the semiconductor elements present inside the process chamber are processed by means of one processing apparatus in each case. Both during the processing procedure inside the process chamber and during transport from process chamber to process chamber, the highly sensitive semiconductor elements must always be present in a protected atmosphere—in particular in an air-free environment. The process chambers are connected to one another, for example, via connecting corridors, it being possible, by means of vacuum gate valves, to open the process chambers for transferring the parts from one manufacturing chamber to the next and subsequently to close said process chambers gas-tight for carrying out the respective manufacturing step. Such valves are also referred to as vacuum transfer valves owing to the field of use described and also as rectangular gate valves owing to their rectangular opening cross-section.
Very different embodiments of vacuum valves, in particular the sealing and drive technologies thereof, are known from the prior art. Depending on the respective drive technologies, a distinction is made in particular between gate valves, also referred to as valve gates or rectangular gates, and shuttle valves, the closing and opening in the prior art generally taking place in two steps. In a first step, a valve closure, in particular a closure disc, in the case of a gate valve, as disclosed, for example, in U.S. Pat. No. 6,416,037 (Geiser) or U.S. Pat. No. 6,056,266 (Blecha), is moved linearly over an opening substantially parallel to the valve seat or, in the case of a shuttle valve, as disclosed, for example, in U.S. Pat. No. 6,089,537 (Olmsted), is pivoted about a pivot axis over the opening without contact taking place between the closure disc and the valve seat of the valve housing as a result. In a second step, the closure disc is pressed with its closure side onto the valve seat of the valve housing so that the opening is closed gas-tight. Sealing can be effected, for example, either via a sealing ring which is arranged on the closure side of the closure disc and is pressed onto the valve seat running round the opening or via a sealing ring on the valve seat, against which the closure side of the closure disc is pressed.
Gate valves are also known in which the closing and sealing process is effected via a single linear movement. Such a valve is, for example, the transfer valve from VAT Vakuumventile AG in Haag, Switzerland, which is know by the product designation “MONOVAT series 02 and 03” and designed as a rectangular insert valve. The design and the mode of operation of such a valve are described, for example, in U.S. Pat. No. 4,809,950 (Geiser) and U.S. Pat. No. 4,881,717 (Geiser). The valve described there has, in its housing, a sealing surface which, viewed in the direction of the axis of the valve passage, has sections which are located one behind the other and become, via continuous curves, flat sealing surface sections running laterally outwards, the imaginary generators of this sealing surface which is in one part but has a plurality of sections being parallel to the axis of the valve passage. The sealing surface is processed. The closure member has a contact surface corresponding thereto for the circumferentially closed seal. Described in more detail, the so-called valve gate has a gate housing and a gate passage which can be closed by a closure member displaceable in its plane. Provided in the region of the gate passage is a sealing surface against which a circumferentially closed seal arranged on the closure member rests in the closed position of said closure member, the imaginary, straight generators of the sealing surface being parallel to the axis of the gate passage. The circumferentially closed, one-piece seal has sections of different lengths and/or shapes which are in different planes, two main sections of the circumferentially closed seal being in planes which are at right angles to the axis of the gate passage and a distance apart. The two main sections of the seal are connected by lateral sections. For running of the sealing surface of the housing, the closure member has a corresponding surface carrying the circumferentially closed seal. The lateral sections and the circumferentially closed seal are U-shaped. In each case the limbs of these U-shaped lateral sections are in a plane. Those sections of the sealing surface which are located one behind the other when viewed in the axial direction of the gate passage become flat sealing surface sections running laterally outwards for contact with the main sections of the seal in that region in which they have a common, straight generator parallel to the axis. These flat sealing surface sections are in planes parallel to one another and to the axis of the gate passage. Since the closure member comprises one part, it can be exposed to high acceleration forces, so that this valve can also be used for fast and emergency closures. Since the closing and sealing can be effected by means of a single linear movement, very fast closing and opening of the valve are possible.
A suitable drive with such a transfer valve which can be closed by means of a linear movement is described in JP 6241344 (Buriida Fuuberuto). The drive described there has eccentrically mounted levers for linear displacement of the connecting rods on which the closure member is mounted.